Respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD), are a significant global health program, with an increasing incidence throughout the world. They are usually characterised by an inflammatory dysfunction of the airways which results in bronchoconstriction.
In asthma inflammation is driven by exposure to a variety of triggers, including allergens and viruses, which activate components of both the innate and acquired immune responses. In COPD inflammation occurs primarily because of exposure to noxious particles and gases, in particular to cigarette smoke. Rather than a single pathologic condition, COPD is a term encompassing several disorders, such as chronic bronchitis or emphysema.
Asthma and COPD are commonly associated with severe impairment of the physical functions as a consequence of pulmonary symptoms such as dyspnoea (breathlessness), fatigue, cough, wheezing, chest tightness or congestion, and sputum production. Many patients with respiratory diseases complain of the serious impact of these symptoms in the quality of their sleep.
In COPD patients, sleep-related complaints are the third most commonly reported symptoms, after dyspnoea and fatigue (Kinsman et al, Chest, 1983, 83, 755-761). In the case of asthma, 80% of the patients are woken at least occasionally by nocturnal wheeze and cough, and many patients with severe stable asthma are woken virtually every night (Turner-Warwick, M.; Am. J. Med., 1988, 85 (suppl. 1B), 6-8).
Sleep complaints frequently reported by respiratory patients are for example longer latency to falling asleep, difficulty in staying asleep, frequent arousals and awakenings, superficial sleep, reduction of total sleep time, waking up too early and not being able to get back to sleep, generalised insomnia and, overall, a much poorer quality of sleep. Excessive daytime sleepiness arid restricted physical activity during the day due to breathlessness in the morning are also common consequences of the impaired quality of sleep.
These sleep disturbances tend to be more severe with advancing disease and substantially reduce the quality of life of respiratory patients.
Bronchodilating agents like the beta-adrenergic agonists or the antagonists of cholinergic muscarinic receptors (commonly known as anticholinergics antirnuscarinics) are usually prescribed for inhalation to respiratory patients suffering from obstructive airway diseases, such as asthma or COPD. commercially available antichohnergics are synthetic tropane derivatives, and include ipratropium, oxitropium, and tiotropium. Tiotropium, is the only long-acting anticholinergic currently on the market.
It is well known that the impact of the circadian rhythm on airway responsiveness and airway resistance is much larger in respiratory patients that in normal subjects. As a consequence, respiratory patients are particularly prone to bronchoconstriction at night and in the early morning hours and this is the main factor affecting the quality of their sleep. Therefore, a treatment aimed at overcoming or preventing bronchoconstriction during the night is highly desirable. However, a study by Calverley el al., in Thorax, 2003, 58 (10), 855-860 shows that the administration of the long-acting bronchodilator tiotropium in the evening does not produce more bronchodilation during the night than when it is administered only in the morning.
It has now surprisingly been found that aclidinium significantly diminishes the occurrence of the sleep disturbances commonly seen in respiratory patients, increasing thus quality of sleep and overall quality of life.
Aclidinium is 3(R)-(2-hydroxy-2,2-dithien-2-ylacetoxy)-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane, a long-acting muscarinic receptor antagonist in development by Almirall for administration by inhalation in the treatment of respiratory diseases, especially asthma and COPD. It was first disclosed in WO 01/04118.
Aclidinium is rapidly hydrolysed in human plasma to two inactive metabolites, and hence has a reduced potential for systemic side effects and a wider safety margin than currently available inhaled anticholinergic treatments. Its additional effect in improving quality of sleep is an unexpected finding of this invention.